Absolute and relative atomic mass values are obtained in kg/atom, MeV, C, and u for the chemical elements. The results show that: (i) Absolute atomic mass value is, of course, given by the classical mass formula m = hϑ/c 2 ; however, rotational speed per radius ω/r correlates with strain τ on the element's intrinsic electromagnetic (e-m) transverse radiation to give the coefficient k whose value turns out to be atomic mass unit energy equivalent amu/eV = k = τ/(ω/r) ½ . (ii) Each component of the wave-particle doublet plays unique roles in atomic mass phenomenology; these roles readily account for H atom's seeming fundamentality and preponderance of internal structures in virtually all particulate matter down to the electron. atomic mass shows that the former redeems the inherent error to retrieve proximate gm from E/c 2 value. (vi) Given the current literature E/c 2 values, the electron waveform mass does converge with the photon's value, i.e., m w(e) ≅ m photon . It is submitted, therefore, that particle physics has already struck matter's fundamental unit in the photon mass, maybe unknowingly for lack of litmus test.